THE FLOWER 



12S 



170. Partridge Berry, with two forms of 

 flowers. 



brought down into the position a' and dust the bee's back 

 with pollen. When the bee withdraws its head, the 

 anthers resume their former station. At a later stage, 

 after the pollen is exhausted or the anther withered, the 

 stigma becomes receptive. It then occupies the position 

 ', and its branches 

 spread to brush pollen 

 from the back of a 

 subsequent visitor. 



241. Partridge Ber- 

 ry (^Mitchell a, Fig. 

 170). The plant 

 grows abundantly, as 

 a small trailing herb 

 with evergreen leaves, 



in open woods. The blossoms are of two forms ; namely, 

 one form (a) with long style and low stamens, the other 



(5) with short style and high 

 stamens (Fig. 171). The sta- 

 mens of form a are at about 

 the same level as the stigma 

 of form b ; and the stamens 

 of b are level with the stigma 

 of a. An insect brushing the 

 stamens of b with its sides 

 will subsequently bring these 

 pollen-dusted sides in contact 



a, long-styled form ; &, short- with the stigma of a. The 

 styled form, of flower in the proboscis of the insect, smeared 



Partridge Berry. ^ 



with pollen from the stamens 



, will leave some of it on the stigma of b. When 

 a species of plants bears two sorts of flowers, as regards 

 the relative lengths of stamens and style, the flowers are 

 said to be dimorphic. In many dimorphic flowers the pol- 

 len of a differs in size from that of b ; and neither kind of 

 pollen is capable of fertilizing the flower that produces it. 



242. The opening and closing of flowers, according to 

 the habits of the insects that pollinate them, opening by 



of 



